Optimize requests in Django admin for DataImports

arkindex/dataimport/admin.py

 from django.contrib import admin
+from django.db.models import Max
 from enumfields.admin import EnumFieldListFilter
 from arkindex.dataimport.models import DataImport, DataFile, Repository, Revision
 
@@ -14,6 +15,11 @@ class DataImportAdmin(admin.ModelAdmin):
     readonly_fields = ('id', 'workflow', 'state')
     inlines = [DataFileInline, ]
 
+    def get_queryset(self, *args, **kwargs):
+        return super().get_queryset(*args, **kwargs) \
+            .prefetch_related('workflow__tasks') \
+            .annotate(last_run=Max('workflow__tasks__run'))
+
 
 class DataFileAdmin(admin.ModelAdmin):
     list_display = ('id', 'name', 'corpus')